In nature, arsenic (As) and iron (Fe) biotransformation are interconnected, influencing local As mobility and toxicity. While As- or Fe-metabolizing microorganisms are widely documented, knowledge concerning their cycling genes, associated with geophysicochemical data and taxonomic distribution, remains scarce. We performed a meta-analysis to explore the distribution and environmental importance of As- and Fe-redox genes (AsRGs and FeRGs) and predict their significant correlations and hosts. The most abundant and ubiquitous AsRGs and FeRGs were arsC and ccoN, respectively. The ccoN gene had the highest frequency at pH ≥ 9.1, in which dissolved Fe(II) is scarce, possibly contributing to enhanced host survival. Fe(III) oxidation genes iro and ccoN appear to be associated with As(V) detoxification in mesophilic environments. No correlation was observed between Fe(III) reduction gene omcB and arsenate reductase genes. Cytochromes with putative roles in Fe-redox reactions were identified (including yceJ and fbcH) and were significantly correlated with As(V) reduction genes under diverse geophysicochemical conditions. The taxonomies of AsRGs and FeRGs-carrying contigs revealed great diversity, among which various, such as Chlamydea (arsC) and Firmicutes (omcB), were previously undescribed. Nearly all (98.9%) of the AsRGs and FeRGs were not carried by any plasmid sequences. This meta-analysis expands our understanding of the global environmental, taxonomic and functional microbiome involved in As- and Fe-redox transformations. Moreover, these findings should help guide studies on putative in vivo functional roles of cytochromes in Fe-redox pathways.

在自然界中，砷（As）和铁（Fe）的生物转化相互关联，影响局部As的迁移率和毒性。尽管广泛地记录了代谢As或Fe的微生物，但有关其循环基因的知识与地球物理化学数据和分类学分布有关，仍然很少。我们进行了荟萃分析，以探讨As和Fe氧化还原基因（AsRGs和FeRGs）的分布和环境重要性，并预测它们的显着相关性和宿主。最丰富的和无处不AsRGs和FeRGs是ARS C和CCO N，分别。所述CCO N基因在pH 9.1≥（II）中的最高频率，其中溶解的Fe是稀少，可能是为了增强宿主的存活促进。Fe（III）氧化基因iro和cco N在中温环境中似乎与As（V）排毒有关。Fe（III）还原基因omc B与砷酸还原酶基因之间没有相关性。与铁的氧化还原反应的推定作用细胞色素鉴定（包括YCE J和FBC H）和与As（V）的多样geophysicochemical条件下还原基因显著相关。携带AsRGs和FeRGs的重叠群的分类学显示出极大的多样性，其中以前没有描述过各种，例如衣原体（ars C）和Firmicutes（omc B）。几乎所有（98.9％）的AsRG和FeRG都不由任何质粒序列携带。这个元分析进一步扩展了我们对涉及As-和Fe-redox转化的全球环境，生物分类和功能微生物组的了解。此外，这些发现应有助于指导有关细胞色素在Fe-redox途径中的体内功能性作用的研究。